Thyroid of Lake Sturgeon, Acipenser fulvescens

We studied the deiodination responses to an exogenous 3,5,3′-triiodothyronine challenge and to a diet-induced growth suppression

James C. Plohman; Terry A. Dick; J.Geoffrey Eales

2002

Scholarcy highlights

  • The authors studied the properties and tissue distribution of thyroid hormone deiodination activities measured in vitro at subnanomolar substrate levels for cultured 2-year-old lake sturgeon held at 12 to 15°
  • We studied the deiodination responses to an exogenous 3,5,3′-triiodothyronine challenge and to a diet-induced growth suppression
  • T4ORD activity was evident in the thyroid, suggesting that it secretes some T3
  • The authors conclude that plasma T3 in lake sturgeon can be derived both from the thyroid and from hepatic T4ORD activity, which varies with sampling time and downregulates in response to a T3 challenge
  • A reduction in plasma T3 accompanying a change in diet and reduced growth was not due to a decrease in T4ORD activity; rather, it was due to an increase in hepatic and intestinal T3IRD activities
  • These results suggest a difference in emphasis in thyroidal regulation between sturgeon and certain teleosts
  • To whom correspondence and reprint requests should be addressed

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